HAADF/EELS/ADF/BF detector

The EELS detector usually consists of a magnetic sector. When an electron travels through a uniform magnetic field perpendicular to its travel, its path is constrained by its velocity (energy). Hence electrons of different energies are focussed at different positions on a focussing plane. There are a number of different detectors that can be used. In our instrument the electrons are focussed onto a CCD array, and this is read out and displayed as a histogram of intensity against energy lost.

The resolution of the information in the EELS spectrum can be better than 1eV, and depends on electron source type and current. The spectrum can give information about both composition and the electronic state of the atom; however detectability is poor as the edges are superimposed on a rapidly sloping background, and errors in quantification are greater than for X-ray analysis.

HAADF detectors:

YAP HAADF detector

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